# Homework Help: What speed & direction?

1. Dec 14, 2007

### Charles C

I know that this should be simple, but I really can't find out how to do this:
A pilot needs to fly at 600km/hr on a bearing of 240 degrees to be on time and on course. A wind is blowing from the west at 60km/hr. In what direction and at what speed should she fly her plane to offset the effect of the wind?

One question I have is when it says "on a bearing of 240 degrees", do you count clockwise or counterclockwise?

I will greatly appreciate any help.

Eh, I think I posted in the wrong area, feel free to to move this.

Last edited: Dec 14, 2007
2. Dec 14, 2007

### Shooting Star

Bearings are generally given as the angle that is measured clockwise from north. Now you can use the formula for relative velocity.

3. Dec 14, 2007

### Charles C

Last edited by a moderator: May 3, 2017
4. Dec 14, 2007

### Shooting Star

Could you explain the diagram?

5. Dec 14, 2007

### Charles C

the speed of the plane is 600, so 600sin30 is 300 and 600cos30 is 519.6. The wind coming from the west is 60, so to compensate for that, I add the 60 to the 300 and get 360. Then I use the Pythagorean theorem to get 632.
Actually, I think I may have done it wrong cause I'm pretty sure I'm supposed to get a different angle.

6. Dec 14, 2007

### Shooting Star

You have to compenste by adding 60 to 600*cos 30. Then you'll get the correct answer.

7. Dec 14, 2007

### Charles C

So it would be 652.64 with theta=30?

8. Dec 14, 2007

### Shooting Star

I'm leaving that to you. You know how to multiply. I have to do something now.

9. Dec 15, 2007

### Shooting Star

Quite correct. Now find the angle in which the plane has to go.